Personal computers and home video game computers use graphics images to visually portray an act or idea. To create graphic images, graphic primitives may be used. “Graphics primitives” are a basic component of a graphics picture, such as a polygon, e.g., a triangle, or a vector. Graphic pictures are formed with combinations of these graphic primitives.
Early graphics systems displayed images representing objects having extremely smooth surfaces. That is, textures, bumps, scratches, or other surface features were not modeled. In order to improve the quality of the image, texture mapping was developed to model the complexity of real world surface images. A texture map is an object. Texture mapping is the mapping of an image or function onto a surface in three dimensions.
Generally, texture compositing is then performed on a texture map. Texture compositing blends two maps together producing a single image which demonstrates various visual effects. For example, one map can represent a traditional texture map while the second map functions as a “light map” which modulates the first map. This produces a diffuse lit appearance resembling static area light sources. Texture compositing is also commonly used to produce such effects as: specular highlights, static Phong shading, and various transparency effects. The source surfaces need not be of the same type or resolution. Both maps may be addressed using a single set of texture coordinates or may have two separate sets of coordinates.
In conventional systems, texture compositing occurs in series. Accordingly only two texture maps undergo texture compositing in a single pass. To perform multiple texture compositing, increased computer equipment is generally required.
It is desirable to have a system that allows for multiple texture compositing while reducing the resources that are necessary to perform multiple texture compositing.